Fortress. Six Degrees, #6

Melinoe doesn't really care about lies and truths, most of the time, because she is a Nymph of Nightmares, after all, but being pregnant with Karma's child, and the child magically disappearing in and out of her womb, taking Melinoe's magic with it... Melinoe's not exactly sure how to broach that subject with Karma, so she decides to try and figure it out herself, before telling him about the baby. Melinoe gets on the train to deepworld, looking for the deepworld shaman, that she'd had a one-night stand with, long before she'd met Karma, to find out what exactly is going on with her and Karma's child. This story has mature subject matter, and concludes Melinoe and Karma's story.
It should be read in series order.